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Visual Secret Sharing Schemes for Plural Secret Images Allowing the Rotation of Shares. Kazuki Yoneyama Wang Lei Mitsugu Iwamoto Noboru Kunihiro Kazuo Ohta The University of Electro-Communications. Basic VSS schemes V.S. Our scheme. Basic visual secret sharing schemes (VSS)
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Visual Secret Sharing Schemes for Plural Secret ImagesAllowing the Rotation of Shares Kazuki YoneyamaWang Lei Mitsugu Iwamoto Noboru Kunihiro Kazuo Ohta The University of Electro-Communications
Basic VSS schemes V.S. Our scheme • Basic visual secret sharing schemes (VSS) • By stacking up shares, each secret image is decrypted. • VSS schemes for plural secret images with general access structures allowing the rotation (VSS-PI-R) • Moresecret images can be decrypted compared with the ordinal VSS. • We can construct any VSS-PI-R scheme for given access structure.
In the case of (2, 2)-threshold Basic VSS Shares Decryption (Stacking up) One secret image VSS-PI-R Shares Decryption (Stacking up) Decryption (180 degrees Rotation and Stacking up) Two secret images
Each code set Bp can be obtained from matrix Bpis called basis matrix s.t. Bp= . Construction of VSS-q-PI schemes Secret images A set of shares A combination of pixels in secret images p(1) V1 p(1)p(2)……p(q) p(2) A matrix representingn pixels with m subpixels V2 A code set Bp p(q) Vn
SU1SU2 SL1R(SU2) SU1R(SL2) SL1SL2 Problem • Relation between shares and secret images The permutation of columns R is used in decryption. Share 1 Rotated Share 2 Share 2 SU2 SU1 R(SL2) R(SU2) SL2 SL1 Decrypted image 2 Decrypted image 1 A code set in VSS-q-PI-R schemes cannot be an equivalence class of some matrix .
Main theorem • A new operation vn • The inverse of vn coincides with vn. [Theorem] (informal)Each code set Bp of the VSS-PI-R scheme can be obtained by Bp = {vn(B) : B }
Conclusion • The proposed technique can easily be applied to VSS-PI schemes allowing to reverse the shares besides stacking in decryption. • We will soon submit the paper corresponding to this talk in Cryptology ePrint Archive!